The endoscope is widely used to examine images of organs or perform surgical operations in a small area. The conventional endoscope usually employs an optical fiber system to capture tissue images by penetrating deeply into hollow organs of a human body (such as the stomach, large intestine and throat) to facilitate determination of the sources and developing conditions of illness. Light is transmitted through an optical fiber cable from a light source to project on the organ tissue. Images are transmitted back through the optical fiber cable to form images on an image sensor. The images are processed by a circuit and displayed on a screen. The optical fiber cable has to include many optical fibers to generate enough pixels. Such an optical fiber endoscope is expensive and complex. Fabrication is difficult, and maintenance is not easy. As the optical fiber endoscope is expensive, it has to be used repeatedly. Infection of patients is prone to occur if sterilization is not done properly. The disposable requirement is the tendency in the future.
Another problem of the optical fiber endoscope is that the flexible hose is too large and often inflicts pain upon the patient. Hence many patients are reluctant to undergo a stomach examination that involves the endoscope. Moreover, the present optical fiber endoscope for the digestive track can examine only the throat, stomach and large intestines. For the small intestines, which have a total length of six meters, the optical fiber endoscope can reach only the first ninety centimeters. Hence most of the small intestines cannot be examined.
In order to resolve the problem of examining the small intestines, referring to FIG. 1, Given image corporation (an Israeli company) has developed a vivo video camera system disclosed in U.S. Pat. No. 5,604,531. It can transmit image data by wireless to facilitate examination of the inner wall of the small intestines.
It is a wireless capsule endoscope 10 including a transparent optical front cover 12 and an opaque capsule shell 13 that are compatible with the human body. After being swallowed by a patient, the digestive tract 11 of the patient is adjacent to the transparent optical front cover 12. A light emitting diode (LED) 14 in the endoscope emits light to pass through the transparent optical front cover 12 and project on the inner wall of the digestive tract 11. Images are transmitted back through the transparent optical front cover 12, an image forming front lens 17a and an image forming rear lens 17b to form the images on a charge-coupled device (CCD) 16. A CCD actuator 15 drives the CCD 16 and sends the image signals to a wireless transmitter 18 for transmission. An antenna is located outside the patient to capture the image signals and send the signals to a reception system. After being processed by a circuit, the images are stored or displayed on a display device to be interpreted by doctors. A power supply module 19 is included to provide electric power for the operation of the entire capsule endoscope.
The wireless capsule endoscope is very helpful for examining the small intestines. However, the direction of the capsule endoscope cannot be controlled. Hence it is not suitable to examine the throat and stomach. As the number of patients suffering from illnesses in the small intestines is less than those suffering from the stomach illness, application of the capsule endoscope are limited.